Objective: Increased interest in fish culture has increased awareness of parasites that affect fish health, growth, and survival. Information obtained in this way made available to the fish culturist as a guide to common parasites of freshwater fish. Sturgeons are susceptible to invasions of parasites during different stages of rearing. This will affect their normal growth and development and also jeopardize their culture. The present study was conducted to determine changes of the parasitic fauna in sturgeon larvae and sturgeon fingerlings and to estimate the prevalence and intensity of parasites and to study the effects of parasite intensity on sturgeon growth. Method & Materials: The study was conducted in two phases from May to July 2006 & 2007, in Shahid Beheshti Sturgeon Hatchery in North of Iran. In the first phase (in each year), 180 sturgeon larvae (5 days after the onset of exogenous feeding) were studied from five Vniro tanks. In the second phase (in each year), 300 sturgeon fingerlings collected from five earthen rearing ponds were studied. The specimens under study were measured and their biometric characteristics were recorded. Standard methods of sampling and parasitological examinations were used. Standard statistical computations were carried out using SPSS and Excel. Results & Conclusion: No parasitic infection was observed in larvae (in Vniro tanks) in two years. This is probably because the rearing period in Vniro tanks is very short and also because the presence of intermediate hosts of parasites is limited in this stage. Other reasons could be lower water temperature in this period as compared to that in earthen ponds. However, Trichodina reticulata were observed in the larvae in the first week (prevalence in 2006 and 2007 = 10%- 20% and 20%-30%, respectively) after they were transferred to the earthen ponds. At the time of their release into the river, in addition to Trichodina reticulata (prevalence in 2006 and 2007 = 13.33% – ۱۰۰% and 56.67% – 100, respectively), Diplostomum spathaceum (prevalence in 2006 and 2007 = 6.67% – 30% and 3.34% – 6.67%, respectively) was also observed in the sturgeon fingerlings. Increase in prevalence of Trichodina infection through the rearing period can be explained by the increase in water temperature and increase in dissolved organic matter in the ponds. Significant differences were detected in the mean intensity of Trichodina reticulata infection in sturgeon fingerlings during the different stages of rearing in earthen ponds in two years (P<0.05).